Improvement in lamp-chimneys



UNITED TAT ROBERT R. CROSBY, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT lN LAMPCHIMNEYS.

Specification forming part of Letters Patent No. 179,958, dated July 14, 1868.

To all whom it may concern:

Be it known that I, ROBERT R. CROSBY, of Boston, in the county of Suiolk and State of Massachusetts, have invented certain Improvements in LampChimneys and I do hereby declare that the following is a full and exact description thereof, reference being had tothe accompanying drawings, making part of this' specification, and representing a side View of a lamp with my improved chimney.

In this invention the chimney B extends below the burner-cone A, the burner being open beneath the cone, except that the chimney surrounds it, whereby the light shines downward beneath the cone and illuminatesl closely around the base of the lamp.

My improved chimney (shown in Figure 3) has its lower portion f, which goes down around the burner, of cylindrical form, or nearly so; then, at about the base of the burner-cone, it is abruptly enlarged, as at g, to a size considerably greater than the said cylindrical part, and thence it is contracted regularly, in a conical form, to the top h, where it is as small as required, all substantially as represented.

This abrupt enlargement of the chimney just around the burner-cone produces an unusually large and wid ely-expanded flame, very steady, and not easily blown out by a blast of air; and the conical contraction upward makes the draft regular, free from eddies, so that the flame burns clear, and if a puff of smoke suddenly starts up, it is not thrown against the inside of the chimney, but passes out freely without coming in contact therewith. Also, the chimney, thus constructed,| may be unusually short.

This abrupt enlargement is nearly or quite at right angles to the base portion f of the chimney, the corners connecting with the sides below and above being rounded oft'.

What I claim as my invention, and desire to secure by Letters Patent, is-

The abrupt or nearly right-angled enlargement of the chimney, as represented in Fig. 3, arranged in relation to the lamp-burner, substantially as and for the purpose herein specified.

The above specification of my improved lamp signed by me this 21st day of January, 1868.

ROBERT R. CROSBY.

'Witnessesz L. W. WARREN, A. H. KNAPP. 

